Atmospheric Autoxidation of Organophosphate Esters

Zihao Fu; Hong Bin Xie; Jonas Elm; Yang Liu; Zhiqiang Fu; Jingwen Chen

doi:10.1021/acs.est.1c04817

Atmospheric Autoxidation of Organophosphate Esters

Zihao Fu, Hong Bin Xie^*, Jonas Elm, Yang Liu, Zhiqiang Fu, Jingwen Chen

^*Corresponding author for this work

Department of Chemistry
iCLIMATE Aarhus University Interdisciplinary Centre for Climate Change - iCLIMATE Aarhus University Interdisciplinary Centre for Climate Change, Langelandsgade

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaper › Journal article › Research › peer-review

26 Citations (Scopus)

Abstract

Organophosphate esters (OPEs), widely used as flame retardants and plasticizers, have frequently been identified in the atmosphere. However, their atmospheric fate and toxicity associated with atmospheric transformations are unclear. Here, we performed quantum chemical calculations and computational toxicology to investigate the reaction mechanism of peroxy radicals of OPEs (OPEs-RO2), key intermediates in determining the atmospheric chemistry of OPEs, and the toxicity of the reaction products. TMP-RO2 (R1) and TCPP-RO2 (R2) derived from trimethyl phosphate and tris(2-chloroisopropyl) phosphate, respectively, are selected as model systems. The results indicate that R1 and R2 can follow an H-shift-driven autoxidation mechanism under low NO concentration ([NO]) conditions, clarifying that RO2 from esters can follow an autoxidation mechanism. The unexpected autoxidation mechanism can be attributed to the distinct role of the -(O)3P(•O) phosphate-ester group in facilitating the H-shift of OPEs-RO2 from commonly encountered -OC(•O)- and -ONO2 ester groups in the atmosphere. Under high [NO] conditions, NO can mediate the autoxidation mechanism to form organonitrates and alkoxy radical-related products. The products from the autoxidation mechanism have low volatility and aquatic toxicity compared to their corresponding parent compounds. The proposed autoxidation mechanism advances our current understanding of the atmospheric RO2 chemistry and the environmental risk of OPEs.

Original language	English
Journal	Environmental Science & Technology
Volume	56
Issue	11
Pages (from-to)	6944–6955
Number of pages	12
ISSN	0013-936X
DOIs	https://doi.org/10.1021/acs.est.1c04817
Publication status	Published - 7 Jun 2022

Keywords

atmospheric oxidation
peroxy radicals (RO)
quantum chemical calculations
secondary organic aerosol (SOA)
volatile chemical products (VCPs)
Atmosphere/chemistry
Phosphates
Environmental Monitoring
China
Esters
Flame Retardants/analysis
Organophosphates

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10.1021/acs.est.1c04817

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@article{74b893af58cf413c9d6bc0e918ce81f2,

title = "Atmospheric Autoxidation of Organophosphate Esters",

abstract = "Organophosphate esters (OPEs), widely used as flame retardants and plasticizers, have frequently been identified in the atmosphere. However, their atmospheric fate and toxicity associated with atmospheric transformations are unclear. Here, we performed quantum chemical calculations and computational toxicology to investigate the reaction mechanism of peroxy radicals of OPEs (OPEs-RO2), key intermediates in determining the atmospheric chemistry of OPEs, and the toxicity of the reaction products. TMP-RO2 (R1) and TCPP-RO2 (R2) derived from trimethyl phosphate and tris(2-chloroisopropyl) phosphate, respectively, are selected as model systems. The results indicate that R1 and R2 can follow an H-shift-driven autoxidation mechanism under low NO concentration ([NO]) conditions, clarifying that RO2 from esters can follow an autoxidation mechanism. The unexpected autoxidation mechanism can be attributed to the distinct role of the -(O)3P(•O) phosphate-ester group in facilitating the H-shift of OPEs-RO2 from commonly encountered -OC(•O)- and -ONO2 ester groups in the atmosphere. Under high [NO] conditions, NO can mediate the autoxidation mechanism to form organonitrates and alkoxy radical-related products. The products from the autoxidation mechanism have low volatility and aquatic toxicity compared to their corresponding parent compounds. The proposed autoxidation mechanism advances our current understanding of the atmospheric RO2 chemistry and the environmental risk of OPEs. ",

keywords = "atmospheric oxidation, peroxy radicals (RO), quantum chemical calculations, secondary organic aerosol (SOA), volatile chemical products (VCPs), Atmosphere/chemistry, Phosphates, Environmental Monitoring, China, Esters, Flame Retardants/analysis, Organophosphates",

author = "Zihao Fu and Xie, {Hong Bin} and Jonas Elm and Yang Liu and Zhiqiang Fu and Jingwen Chen",

note = "Funding Information: This study was supported by the LiaoNing Revitalization Talents Program (XLYC1907194), National Natural Science Foundation of China (21876024) and the Major International Joint Research Programme (21661142001). We thank for computing support by Supercomputing Center of Dalian University of Technology. Publisher Copyright: {\textcopyright} 2021 American Chemical Society.",

year = "2022",

month = jun,

day = "7",

doi = "10.1021/acs.est.1c04817",

language = "English",

volume = "56",

pages = "6944–6955",

journal = "Environmental Science & Technology",

issn = "0013-936X",

publisher = "American Chemical Society",

number = "11",

}

TY - JOUR

T1 - Atmospheric Autoxidation of Organophosphate Esters

AU - Fu, Zihao

AU - Xie, Hong Bin

AU - Elm, Jonas

AU - Liu, Yang

AU - Fu, Zhiqiang

AU - Chen, Jingwen

N1 - Funding Information: This study was supported by the LiaoNing Revitalization Talents Program (XLYC1907194), National Natural Science Foundation of China (21876024) and the Major International Joint Research Programme (21661142001). We thank for computing support by Supercomputing Center of Dalian University of Technology. Publisher Copyright: © 2021 American Chemical Society.

PY - 2022/6/7

Y1 - 2022/6/7

N2 - Organophosphate esters (OPEs), widely used as flame retardants and plasticizers, have frequently been identified in the atmosphere. However, their atmospheric fate and toxicity associated with atmospheric transformations are unclear. Here, we performed quantum chemical calculations and computational toxicology to investigate the reaction mechanism of peroxy radicals of OPEs (OPEs-RO2), key intermediates in determining the atmospheric chemistry of OPEs, and the toxicity of the reaction products. TMP-RO2 (R1) and TCPP-RO2 (R2) derived from trimethyl phosphate and tris(2-chloroisopropyl) phosphate, respectively, are selected as model systems. The results indicate that R1 and R2 can follow an H-shift-driven autoxidation mechanism under low NO concentration ([NO]) conditions, clarifying that RO2 from esters can follow an autoxidation mechanism. The unexpected autoxidation mechanism can be attributed to the distinct role of the -(O)3P(•O) phosphate-ester group in facilitating the H-shift of OPEs-RO2 from commonly encountered -OC(•O)- and -ONO2 ester groups in the atmosphere. Under high [NO] conditions, NO can mediate the autoxidation mechanism to form organonitrates and alkoxy radical-related products. The products from the autoxidation mechanism have low volatility and aquatic toxicity compared to their corresponding parent compounds. The proposed autoxidation mechanism advances our current understanding of the atmospheric RO2 chemistry and the environmental risk of OPEs.

AB - Organophosphate esters (OPEs), widely used as flame retardants and plasticizers, have frequently been identified in the atmosphere. However, their atmospheric fate and toxicity associated with atmospheric transformations are unclear. Here, we performed quantum chemical calculations and computational toxicology to investigate the reaction mechanism of peroxy radicals of OPEs (OPEs-RO2), key intermediates in determining the atmospheric chemistry of OPEs, and the toxicity of the reaction products. TMP-RO2 (R1) and TCPP-RO2 (R2) derived from trimethyl phosphate and tris(2-chloroisopropyl) phosphate, respectively, are selected as model systems. The results indicate that R1 and R2 can follow an H-shift-driven autoxidation mechanism under low NO concentration ([NO]) conditions, clarifying that RO2 from esters can follow an autoxidation mechanism. The unexpected autoxidation mechanism can be attributed to the distinct role of the -(O)3P(•O) phosphate-ester group in facilitating the H-shift of OPEs-RO2 from commonly encountered -OC(•O)- and -ONO2 ester groups in the atmosphere. Under high [NO] conditions, NO can mediate the autoxidation mechanism to form organonitrates and alkoxy radical-related products. The products from the autoxidation mechanism have low volatility and aquatic toxicity compared to their corresponding parent compounds. The proposed autoxidation mechanism advances our current understanding of the atmospheric RO2 chemistry and the environmental risk of OPEs.

KW - atmospheric oxidation

KW - peroxy radicals (RO)

KW - quantum chemical calculations

KW - secondary organic aerosol (SOA)

KW - volatile chemical products (VCPs)

KW - Atmosphere/chemistry

KW - Phosphates

KW - Environmental Monitoring

KW - China

KW - Esters

KW - Flame Retardants/analysis

KW - Organophosphates

UR - http://www.scopus.com/inward/record.url?scp=85119951091&partnerID=8YFLogxK

U2 - 10.1021/acs.est.1c04817

DO - 10.1021/acs.est.1c04817

M3 - Journal article

C2 - 34793133

AN - SCOPUS:85119951091

SN - 0013-936X

VL - 56

SP - 6944

EP - 6955

JO - Environmental Science & Technology

JF - Environmental Science & Technology

IS - 11

ER -

Atmospheric Autoxidation of Organophosphate Esters

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